Process, and system of apparatus, for desiccating foodstuffs



A. w. KOON May 20, 1930.

Rooms AND SYSTEM OF'APPARAH'IZUS FOR DESICCA'I'ING FOODSTUFFS Fi ledSept 7, 1929 2 Sheets-Sheet l May 20, 1930. A. w. KOoN 1,759,702

I PROCESS AND SYSTEM OF APPARATUS FOR DESICCATING FOODSTUFFS Filed se p.7, 1929 2 Sheets-Sheet 2 g x [q 1: \1

Patented May 20,1930

UNITED STATES PATENT OFFICE" LRTHUR W. KOON, OI THIBODAUX, LOUISIANA,ASSIGNOR' TO ARTA MAY KOON, OI NEW ORLEANS, LOUISIANA PnooEss, ANDsvs'rr'm or APPARATUS, non nEsIocA'rIno roonsrurrs Application filedSeptember 7, 1929. Serial No. 390,999.

This invention relates to processes of desiccating moist solids andsemi-solids which are in such a divided condition that they may becarried in a travelling gaseous medium, and to a system of apparatus forcarrying the same into effect. More particularly, it is concerned with aprocess and'apparatus for treating, e. g. curing;freshly-cut, immature,for; age crops, .and drying matured seed crops, other foodstuffs, andthe like.

It is well known that the climatic conditions which best promote thegrowth of forage crops, grain crops and the like,i. e. humidatmosphere,and frequent rains,--are those which interfere to'the greatest extent 7with the natural curing of such products in preparation for storage forlater use in the feeding of animals. An object-of the present invention,therefore, is to provide a commercially practicable process andapparatus for the artificial curing or drying of the aforementionedproducts.

.My invention embraces a cyclical process involving, in each cycleintroducing the material to be desiccate ,in such a divided conditionthat it may be carried in a travelling gaseous medium,-into a current ofa suitably proportioned mixture of steam and inert gaseous products ofcombustion at a 80 temperature well above the dew-point of water, e. g.at a temperature of from about 300$ to about 1200 F., maintaining freesuspension of the material in said medium during the travel of thelatter for a' relatively brief period of time, durin the course of whichtravel the material is mechanically treated, separating the materialfrom the medium out of contact with atmospheric air and while the mediumis still at a temperature materially above the dew-point of water,repeat- 7 ing the cycle with re-use of gaseous medium afterre-conditioning the same, and finally. suddenly cooling the material toapoint/ he?" low the ignition point of the same.

I have chosen as being a particularly desirable drying medium, a mixtureof steam and inert gaseous products 'of combustion (i. egases incapableof supporting combustion of the material); In the course of a cycle thenormal ratio between content of steam from the material undergoingdesiccation and content of the other gaseous components in the preferredmedium becomes unbalanced by reason of the addition thereto of steam 7and -the temperature of the medium drops considerably. Consequently, itis desirable, before re-use of the medium in another cycle, to heat themedium and to balance the ratio by an addition thereto of the othergaseous components of the medium. It is this addition of heat and hotgaseous products of combustion, or/and steam, to which I refer in theexpression re-conditioning.

' The complete cyclical process of the present invention is carried out,down' to but not including the final operation of chilling thedesiccated material, under practically complete exclusion of atmosphericair. By this I mean that air is excluded in so far as posfible in allstages of the process except the The temperatures of the treatments mustwater,-of the order of say from 300 to 500 F. Where after-germination isnot a consideration, the treatments may be effected at temperatures ofthe order of from 500 to 1000 F. or somewhat higher. In general, Iprefer to so operate that in the first cycles the temperatures arematerially vhigher than in the latter cycles.

The number. of treatments resorted to in the cyclical process likewiseis determined by the character,-e. g. moisture content and the like,ofthe materialto be desiccated. Thus in 'a case wherethe material is only"semi-solid and contains a relatively large amount of moisture,such, forinstance, as fish scrap, tankage, and the like,as many as five or sixcycles may be found to be necessary, whereas-in the case of a solidmaterial, such as a mature grain, the number of cycles may be reduced toas few as three or even two. v

The invention embraces not only the procfor carrying the process intoeffect. This system or plant is characterized as follows: For effectinga single treatment (i. e. cycle) in accordance with thehereinbefore-described process a unit of the system comprises in combination a circuitous conduit (preferably, suitably lagged to preventundue loss of heat),'means for causing a'stream of the gaseous dryingmedium to circulate therein (e. g. the commonly known blower, or acirculation fan), means on the suction side of said circulation meansfor introducing divided material undergoing desiccation treatment intosaid conduit and said stream (which may be any suitable devicefordelivering divided solids without substantialinclusion of air, such as,for instance, a self-sealing dumping gate), means on the pressure sideof said circulation means for separating from the said medium solidmaterial carried thereby (such, for instance, as a centrifugal s'eparater), and means,between the said separating means and the said meansfor introducing material undergoing treatment,-for heating said gaseousdrying medium and for adding thereto gaseous products of combustion.

It is a feature of the present inventionthat the last of the above-namedmeans (i. e. the means for heating the gaseous medium and for addingthereto gaseous products of combustion) may be caused to be common to aum, and conduit openings near the'top of -a conduit communicatingbetween said said outer chamber and above said inner chamber for thedrawing off of re-conditioned gaseous drying medium. The gases to beheated and conditioned pass into the heating chamber at a point orpoints near the bottom thereof, and circulate upwardly, serving to coolthe refractory walls of the inner combustion chamber and as well'coolthe inside portions of the walls of the heating chamber. The walls ofthe latter chamber are, of course, suitably insulated to diminish heatlosses.

A unit of apparatus, then, may comprise, in combination, a furnace, ablower or circulation fan for drawing gaseous drying medium therefrom, aconduit communicat ing therebetween and provided with a charging, devicefor solids, a'centrifugal collector,

blower and said collector, and a conduit communicating between saidcollector and said furnace, said charging device being a communication'betweenethe said conduit and a source of solid material undergoingdesiccation treatment,- such, for instance, as the centrifugal collectorof the next preceding unit vided, material is initially treated withpar-.

tially exhausted gaseous drying medium from one of the later dryingunitsof the system. In cases where the system is to operate uponmaterials which are not relatively heavily'saturated with moisture andwhic are not of a gummy nature, the pre-heating unit may comprise avertically disposed, conically-bottomed, c lindrical chamber providedwith means or agitation. Material to be desiccated is delivered, individed condition and without excess of air, into this chamher at apointnear the top thereof, and gas,- eous drying medium from the finishdrying unit collector is led thereinto at a pointnear the base of thechamber and is contacted with the divided material by the aid of themechanical agitation. The resulting fully depleted gas is separated out,and the material,

thus pre-heated, is delivered into the heating conduit of the firstdrying conduit by means of a charging device asdescribed above. Or,

in cases where the material to be desiccated is relatively heavilysaturated and of a gummy nature, the pre-heating unit may take somewhatthe form of a typical drying'unit, differing therefrom in that (1) theconduit, Within which the material is introduced into the current ofgaseous drying medium, communicates between the suction side of a blowerand the gas outlet port of the centrifugal collector of one ofthe laterunits of the system; and (2) the chargin device for admission ofmaterial into this pre-heating unit is associated not with the materialout:- let of a centrifugal collector but with a device for dividing thematerial to be desiccated. The-latter-named device may well take theform of a known ensilage cutter.

Following the last drying unit is a unit for thesudden cooling of thedesiccated product. This comprises a conduit open at one end to the airand at the other end communicating with any suitable receivingreceptacle or storage space, in whlch conduit are interposed-a blowerand, on the suction side of the blower and between the latter and thesaid open end of the conduit, a meansfor delivering thereinto desiccateddivided material from thefinal centrifugal collector (e. g., thehereinbefore-described self-sealing dumping gate). The capacity of theblower is so adjusted with respect to the inflow of desiccated dividedmaterial,-that the material blowing into this final unit of the systemis blasted with a relatively very large volume of atmospheric air,whereby suddenly to cool the material to below its kindling tempera- Iture. v

The invention, in its double aspect of process and system of apparatus,will be more fully understood by recourse tothe accompanying drawings,in which:

Fig. 1 is a diagrammatic representation of a system of apparatusillustrating a preferred embodiment of the process according to thepresent invention; and

Fig. 2 is .a diagrammatic representation of an optional form ofpre-heating'unit for use in the system of apparatus illustrated in Fi 1.A

Kccording to Fig. 1which illustrates a system comprising, incombination, one preheating unit, five heating units, and one unit forthe final sudden cooling of desiccated material,1 is a chopper orequivalent means which delivers divided material, without materialinclusion of air, directly into the agitator-equipped preheating chamber2. 2 is a discharge vent for depleted gases, and 2 is a charging devicecommunicating between chamber 2 and conduit 3. is a conduitcommunicating between the discharge port of centrifugal collector 34 andchamber 2. l

Preheated material, which settles out of contact with gaseous medium and"into thebottom of chamber 2, is delivered by means of charger 2 intoconduit 3 where it is introduced into a stream of gaseous drying mediummoving therein -from furnace 9. In

, said stream the material is conducted into and through the blower 4and thence into centrifugal collector 5. The here-se arated mediumpasses in part to furnace 9 t rough conduit 13, and in part toatmosphere through outlet 14 by means of the pressurec'ontrol damper 5.This represents the first of the five drying units.

Material separated in collector 5 is delivered by means of charger 6into conduit 7 where it is introduced mto a stream of medium carriedthereto by conduit 8 from the furnace 9. In said stream the material isconducted. into and through blower 10 and thence through conduit 11-into collector 12. The here-separated medium passes to furnace'9 throughconduit 13. This represents the second of the five drying units.

The third dryin unit comprises charger 16, conduits 17 an .18, blower19, conduit 20, collector 21, and conduit 22. .The fourth drying unitcomprises charger 23, conduits 24 an '25, blower 26, conduit 27,collector 28,

and conduit 29. The fifth drying unit com prises charger 30, conduits 31and 31', blower 32, conduit 33, collector 34 and conduit 35.

As will be obvious to one skilled in the art, the elements of thereheating unit and of the several drying units-including preheatingchamber 2, the several centrifugal collectors, the conduits, and thelike,preferably are suitably lagged or insulated against heat losses.

In thea'foresaid cooling unit, material is withdrawn from collector 34by means of charger 36 and dischar ed into conduit 37. 38 represents aninlet in atmospheric air. The material-so discharged is blasted with alarge excess of air, passes. into and through blower 39, andis-discharged,-cooled,--into suitable storage or receiver 40. 41-repreered from chopper 1 through charger 42 and by means of conduit 43into a drum preheater 44, which is similar to the known inclined orhorizontal cylindrical drier, with inner spiral flights, capable when inmotion of delivering material from the intake to the discharge endthereof,.where it is intimately contacted with partially exhaustedgaseous dryingmedium, in a stream delivered to the pre-heating unit fromcollector 34 through conduit 35. Thereafter, the material dischargedfrom drum drier 44 is delivered .to a preheatin chamber 2 where it againis contacted wit another portion of the saidpartially exhausted gaseousdrying medlum ed from conduit 35, by means of an adjustable deflector 45through conduit 46 into the lower ortion of prehe'atingchamher 2. 47 isa c arger which serves to deliver preheated material from collector 2into conduit 3 of the first unit stage of drying.

48 and 49 are venting means for discharging used gaseous medium fromandchamber 2, respectively.

The invention will be described. with greater particularity in thefollowing, it be-- ing understood that the scope of the invention is notrestricted thereby.

longitudinally through a chopper of the en-,

silage cutter type, and the divided-material continuously isintroduced,--without inclusion of a substantial amount of air,into andcontacted with a body of partially exhausted Y gaseous drying med um,comprising steam erable modi- I drum drier 44 I partly by the aid ofmechanical and inert gaseous products of combustion, at a temperature ofabout 708 F., maintained in a pie-heating chamber. The divided materialis suspended in the body of the medium, agitation, for a prolonged time.The pre-heated, divided, material gradually is precipitated by gravityfrom the gaseous medium, which latter is vented to the atmosphere.

The pro-heated divided material continuously is withdrawn from thebottom of said chamber by means of a charger, introduced into a streamof the gaseous drying medium at a temperature of about 1800" F. issuingfrom the furnace, and carried therein into and through a blower andthrough the drying pass, and into'a centrifugal collector. During thiscontact between gaseous drying medium and material the latter yields tothe former a considerable amount of water, in the form of steam. Atleast a part of the gaseous medium is returned to the furnace for ie-conditioning (i. e., for addition thereto of heat and of gaseousproducts of combustion) and a part may be vented-to the atmospherethrough a suitable pressure-control damper.

The material, withdrawn from the bottom of the centrifugal collector bymeans of a charger, thereafter is subjected to a third and a fourthdrying treatment substantially equivalent to that just described; thatis to say, in each cycle of treatment a stream of the material isintroduced continuously into a stream of gaseous drying medium (issuingfrom the furnace) at a temperature of about.

1000 F.; is carried in said stream into and through ablower andthereafter into a centrifugal collector where separation of materialfrom medium is effected. The medium is thence returned to the furnacefor re-conditioning.

The fifth or final drying treatment to which the material is subjectedis equivalent torthe four preceding treatments, the cycle of operationsin this latter treatment differing from the preceding ones in that,after the separation of the fully desiccated material from the medium ina centrifugal collector, the separated medium (which in this final stageof the process is not substantially unbalanced in ratio between contentof steamandcontent of gaseous products of combustionbecause of the factthat in said final drying treatment there remained but'little moisturein the material to be extracted) is not returnedtothe furnace forre-conditioning but i rather is diverted to a pro-heating treatment offresh material.

An essential element of the process is the step of suddenly reducing thetemperature of the'fully desiccated and very hot material to below theignition point thereof. This is effected bycontinuously withdrawing thematerial, from the centrifugal collector of tion, and the conduits arefabricated from lighter sheet metal-in order. to aid in the rapidtransfer of heat away from the material.

This final operation of sudden cooling is absolutely necessary, in thatin substantially each instance where it has been attempted;-experimentallyg- -to avoid the cooling step and discharge thematerialdirectly from the collector of the final drying cycle, the material hassuffered spontaneous combustion. lf heat were left in the finallydesiccated ma tcrial the latter would suffer from progressive cooking,with attendant discoloration, and thus would lose some of the advantagesof this process of instantaneous drying at high temperatures.

When the drying of fodder crops has been carried out in accordance withthe process herein described and claimed, the resultant product has arich green color, is sweet, and

' heating cycle, fully desiccated material beginsto be discharged atstorage.

As will be obvious from the foregoing, the number of necessary dryingcycles in the carrying out of the process is determined by the characterof the material to be desiccated.

Thus in operating upon a. material of relativelylow moisture content,such as, for instance, fully matured rain, less moisture is present tobe extracte and the number of necessary drying cycles is correspondinglydiminished.

I have found that matured crops may not only be dried satisfactorily inaccordance with this process, butalso' thrashed, hulled and/or milled(i..e. the outer layers of the grains removed). chanical treatments ofmaterial rain-containingproducts all are efi'ectable 1n accordance withthe foregoing process. 4 A

I have given theoretical consideration to the process of the presentinvention, and believe that the exceptional'success of the same may beexplained in part by the following:

These well-known mev The hi h tem erature of the inert gases which rstare rou ht into intimate contact relation with the divided materialgreatly expands the outer layers of water cells or blad the highlyheated inert gases, are expanded and then ruptured by the succeeding fanblades. By virtue of the several repetitions of the drying treatment,the substantially Whole moisture content of the vegetable it fully.Aside from theoretical, explanastructure is released and. separated, anda fully-desiccated product is obtained. The particular medium employedalso explains the eificiency. The major portion ofthe medium is steam,which ordinarily is supplied by the material treated. Steam from anoutside source may of course be employed, and is employed at thestarting of the process. I find that combustion gases alone provide adisadvantageous medium, in that they parch the. material and frequentlydo not desiccate tions, it is established that the fibrous prod notobtained by the carrying out of my process is fully desiccated, insteadof having merely the outer coverings of each structure dehydrated. A newresult is attained, in that the fully desiccated forage keepsindefinitely, and may be exposed for a protracted atmosphere withoutliability of spoilage.

The invention embraces not only the abovedescribed concrete embodimentsbut as well modification thereof which naturally .will

' suggest themselves to one skilled in the art to which it appertains. 4

What I claim is: I 1. A process for desiccating fodder, forage and likefoodstufl' materials which comprises introducing the material to bedesiccated into a current of a gaseous drying-me dium consisting of asuitably proportioned mixture of steam and inert gaseous products ofcombustion at a temperaturematerially above the dew-point of water,maintaining free 'suspension of the material in said medium during thetravel of the latter for a relatively briefperio'd of time duringthecourse of which travel the material is mechanically treated, andseparating the material from the medium out of contact with air andwhile the medium is still at a temperature materially above thedew-point of water.

2. A'process for desiccating fodder, forage and like foodstuff materialswhich comprises introducin the material to be desiccated into a current0 a gaseous drying medium consisting of a suitably proportioned mixtureof steam and inert gaseous products of'combustion at a temperaturematerially above the dew-point of water, maintaining free sustion pointof the material.

3. A cyclical process for desiccating foddcr, forage and like foodstuflsmaterials, involving, in each cycle, introducing the materials,involving, 111 each. cycle, introducing the material to be desiccated,inv a divided condition, into a current of inert gaseous drylng mediumat a temperature materially above the dew-point of water, maintainingfree suspension of the material in said medium dur- 1n bri ef period oftime during the course of which travel the material is mechanicallytreated, separating the material from the medium out of contact withair, repeating the cycle with re-use of the gaseous medium afterre-conditioning of the same, and finally suddenly cooling the materialto a point below the ignition point of the material.

4. A cyclical process for desiccating fodder, forage and like foodstufimaterials, involving, in each cycle terial to be desiccated, in adivided condition,

into a current of a gaseous drying medium or: contact with air and whilethe medium is st1ll at a temperature materially above the dew-point ofwater, repeating the cycle with re-use of the gaseous medium afterre-conditioning of the same, and finally suddenly cooling the materialto a point below the ignition po1nt of the material.

5. A cyclical process for desiccating fodder, forage and like foodstuffmaterials, comprising dlviding the material, introducing the the travelof the latter for a relatively introducing the madivided material into asuspending current I of partially spent inert gaseous drying medium froma final desiccation treatment'of a previous quantity of material at atemperature materially above the dew-point of water, maintaining freesuspension of the material in the partially spent medium during thetravel of thelatter for a relativelybrief period of time during thecourse of which travel the material is mechanically treated, separatinthe material from the partially spent me ium out of contact with airwhile the medium is still at a temperature materially above thedew-point of water and exhausting the resulting spent medium to theatmosphere' subjecting the separated material to a plurality of dryingtreatments involving, in each cycle, introducin the material into a Isuspending current gaseous drying medium consisting o1 steam and inertgaseous products of combustion at a temperature of the order of 1000 F,maintaining free Y suspension of the material in the medium during thetravel of the latter for a relatively I brief period of time during thecourse of which travel the material is mechanically treated, separatingthe material from the medium out of contact with air, and reconditioningthe separated medium for re-use, and finally suddenly cooling thematerial to a point below the ignition point of the material by blastingwith air. I 6, A system of apparatus for carrying out the processdefined in claim 3, comprising, in combination a plurality of units,each of which consists of a circuitous conduit, means interposed in saidconduit for causing a stream of gaseous drying medium to circulatetherein, means on the suction side of said circulation means forintroducing divided material undergoing desiccation treatment into saidconduit and said stream, means on the pressure side of said circulationmeans for separatingfrom the said medium material carried thereby, andmeans between the said separating means and the said introduction meansfor heating at least a portion of the gaseous drying medium and foradding thereto inert gaseous products of combustion, and a dischargeconduit open at both inlet and outlet and communicating with theseparation means of one of said units, in which discharge conduit thereis interposed, be

tween the said separation means and the outlet, means for thecirculation therethrough of air.

In testimony whereof, I affix my signature.

ARTHUR W. KOON.

